Coal-pulverizing machine



c. E. BLYTH.

COAL PULVERIZ ING MACHINE Filed April 13. 1926 2 Sheets-Sheet 2 itlPatented CHARLES EDWARD BLYTH, 0F STOCKTON. NEAR RUGBY, ENGLAND,ASSIGNOR TO ALFRED HERBERT LIMITED,OF BUTTS, COVENTRY, ENGLAND, ABRITISH COM- JPANY.

COAL-PULVERIZING MACHINE.

Application led April 13, V1926, Serial No.

rll`his invention relates to coal and similar pulverizing machines, ofthe type shown in my prior patent Reissue No. 16,229, in which a streamof air passing through the machine carries the finely powdered coal insuspension, whilst means are provided to return to the pulverizingchamber such particles .of coal as have not attained a suiiicient degreeof iineness, and its object is to provide mechanism for this purposewhich will be effective and inexpensive as well as easy to renew it'necessary. i

In such apparatus, a rotor disk is mounted centrally of the casingbetween an inlet for airand coarse material and a centrally locatedoutlet to provide two pulverizing zones which communicate annularlyaround the periphery of the rotor. The disk is pro- `vided with rows ofpegs on cach side which interfit and cooperate with rows of stationarvpegs on the two opposed casing walls. yllhe coarse material is groundpreliminarily in the inlet zone and is then drawn by a fan adjacent theoutlet around the disk and into the final pulverizing zone. Here theInaterial must be subjected to the impacts of the rapidly revolving pegson the rotor as it is drawn inwardly towards the centrally locatedoutlet.

According to this invention, in the eXit from the pulverizing chamber isemployed a rejector device constituted by one or more rotating membersadapted to traverse the outgoing stream and to throw back into thepulverizing mechanism the heavier particles of coal. Thus until suchparticles attain the necessary degrl of tineness they are repeatedlyreturned into the pulverizer tor further treatment.

A ring adapted to guide the path of the reJected particles mayvalso beprovided to increase the e'ectiveness of the rejector device inreturning the larger coal particles to the pulverizer mechanism.

ln the accompanying drawings, illustrating the application ot theinvention to a lrnown kind of pulverizing machine,

Figure 1 is a diagrammatic sectional view of the machine,

Figure 2 is a fragmentary view of apart oit' the machine showing oneform of rejector device, to a larger scale than Figure 1, and

.Figure 3 is an end view of Figure 2.

101,805, and'in Great Britain May is, 1925.

The machine shown diagrammatically in Figure 1 colnprises a pulverizingchamber 2. having' fixed beaters 3 and rotating beaters 4 carried by amain shaft 5 on which also is mounted a `fan (not shown) located in acasing 6 beside the pulverizer chamber.

Coal is fed through the passage 7 and at the lower part 8 encounters anupward draught ot air created by the fan, which sweeps it through thebranch 9 into the pulverizing chamber 2, from which it passes eventuallyby way of a central exit aperture 10` into the fan casing, and thence tothe burner. I n u It is at this exit aperture 10 that it is 1mportantnot only to prevent the discharge of such particles of coal as are notsutiicientlv reduced in-'size, but also to provide for their return tothe pulverizing chamber for further treatment. Y

Accordingly, therefore, the rejector dcvice is a rotating striker in theform of a4 part ot' the pulverizer.

The shape of the blade may be such that its root 13 is in the plane ofthe exit aperture 10, this being provided in a diaphragm plate 14dividing the pulverizing chamber from the fan chamber, whilst the tip 15of the blade is within'the pulverizing chamber itself. A screen or guidering 16-may be yarranged aroundthe edge of the exit aperture on the sidetowards the pulverizer, so that the tip of the blade is within the ring.The'inner face of the ring may be flared or belled outwardly, as at 17,'towards the pulverizing chamber, and this serves to guide back into thelatter the heavier particles of coal upon which the blade acts. rlhescreen ring may be provided with a radial flange 18 to enable it to bedetachably mounted upon the diaphragm plate 14, or on a plate 19 towhich the fixed beaters 3 are attached.

The blade may be ot channel section with the open part 20 ot the channelas the lead ing. side,.and the depth of the channel may increaseprogressively :trom the root to the tip. Also the blade, andparticularly the bottom wall oia its channel would be curved backwardlyof its direction of rotation (indicated by the arrow) in the manner of acentrifugal tan blade. the blade at the root, the side flanges ot the Togive stiffness to channel may be extended on each side of the portionforming the base of the channel, and/orl there may be a stilfening web21 behind it, and a laterally projecting flange or base plate Q2 may beprovided at the base to enable the blade to be secured radially tothehub member l2 or the like on the shaft 5 which carries it. One bladealone generally suffices, but two, three (as shown) or more may beemployed if desired.

In action, the pulverized coal passes through the aperture 10 from thepulver-izing chamber into the fan chamber, and the rotating striker orblade 11 traverses the outgoing stream and acts upon the heavierparticles of coal, flinging them back into the mechanism within thepulverizing chamber.

lVith this arrangement a very simple and effective device is providedfor rejecting the heavier particles of fuel and for returning them intothe pulverizingnmechanism for further treatment, whilst the constructionemployed is initially inexpensive and also cheap to renew. Furthermore,the use of balles or other devices which would obstruct the outflow ofthe finely pulverized material is avoided.

What I claim as my invention and 'desire to secure by Letters Patent ofthe United States isz- 1. A pulverizing apparatus comprising a casinghaving a centrally located outlet, 1mpact members mounted to revolvesubstantially concentrically with the outlet, means for introducing airand material to be pulverized to the peripheral zone surrounding theimpact members, means to move the air and pulverized material towardsthe outlet, and radially projecting rejeetor blades mounted to revolveclose to the outlet, each of which has an open ended substantiallyradial channel which slopes inwardl)v and is arranged to scoop coarsematerial from the air current passing the blades and hurl it inwardlytowards the impact members.

2. A pulverizing -apparatus comprising a casing having an inlet forairand coarse material and a centrally located outlet, impact membersrevoluble about the outlet to pulverize the material l'ed thereto. and aradially projecting rejector blade mounted to revolve close to theoutlet and scoop coarse particles from the air current, said bladehaving a channel which faces in the direction of revolution and whichincreases in depth from its inner to its outer end.

3. A rejector for use in a pulverizing apparatus comprising a channelshaped member provided with a laterally projectin base plate integraltherewith arranged to [be secured to a rotatable shaft, the channel ofsaid member being open at its outer end so that material caught therebymay be hurled outwardly therefrom.

4. A rejector for use in a pulverizing ap paratus comprising a channelshaped member adapted to revolve and scoo n coarse ma terial from an aircurrent Wiich is provided with a laterally projecting base platearranged to be secured to a rotatable shaft, the channel shaped memberbeing so shaped that the bottom of the channel inclines backwardly withrespect to a radial line and its direction of revolution.

In testimony whereof I have signed my name to this specification.

CHARLES EDWARD BLYTH.

